Tuesday, September 13, 2005

Geography for Dummies

I'm flying out of California this week, and this particular route leaves little time for reading or writing. So, I recycle.

This is part of a continuation entry to my journal from a few weeks ago during the final phase of training from my upgrade. (Again, my apologies to those who have read this already.)

OK, geography lesson. Our route to and from DSM [Des Moines] brings us pretty consistently over Colorado Springs and the Grand Canyon, and I had another opportunity today to look at things in some detail, though there were storm clouds obscuring the Canyon and Vegas. (I’d love to bring along some binoculars and a good camera, except that this is probably the last time I’ll fly in daylight for the next decade.) The Grand Canyon is part of a much, much larger stretch of land--a geological formation or condition or happening or whatever--which appears mostly flat and which shows the effects of severe erosion in very steep, carved river valleys throughout. (I wonder if this is all an ancient sea bed?) There are rivers everywhere in the world, but in most cases it must be the vegetation that slows down the erosion. Here in the high desert, without vegetation of any kind, erosion runs absolutely rampant, or such is how it looks. The entire region is a function of erosion, for miles and endless miles in every direction. Whatever the reasons, the rivers here appear very different from any river you see in the Midwest, including ones with sheer rock faces like Wisconsin Dells. This is just a whole different scale.

The region begins, whatever it’s called, as we encounter the fantastic and surreal Monument Valley (where John Wayne filmed so many great old Westerns with John Ford) and see this hostile change from mountains with tree lines and snow caps to absolutely arid desert with evidence of vast erosion. The landscape below looks a bit like the surface of those old punched-metal discs which played tunes on an antique music box. The relatively flat ground is punctuated with nubs--the “momuments” of Monument Valley--which stand absolutely straight up from the surrounding terrain; there are many, many of them. The region is not actually completely flat, but is made up of a series of flat-ish planes which have exposed cliffs where it appears a 2,000’ thick layer was laid upon an existing layer. So there are these sheer cliffs, which, like the canyons where the rivers flow, expose an amazing pattern of strata in fantastic colors, layer upon layer. A geologist could make quick and fascinating sense of it all. The rivers continue to twist and wind at the bottom of the canyons, and it’s all a bit like looking at the very passage of time itself.

The whole business reminds you not only that the earth itself is impossibly huge (which makes you think that the gas giant planets are hundreds of times larger yet), but that the forces that formed it all are immense beyond comprehension. To think of forces pushing these mountains up in a collision of moving plates is something so far beyond our experience that you can’t really put a finger on it, like contemplating “astronomical” numbers (what does “one billion” mean in any useful sense to us?). To see these rivers wearing vast parts of the earth away, one pebble at a time, until miles upon hundreds of miles of river have exposed the interior of the earth thousands of feet deep on both sides for all these hundreds of miles; it kind of takes your breath away.

As a kid I used to think of the Rocky Mountains as a couple lines of peaks with lowlands on either side. But as you leave the Midwest heading West the elevations rise steadily from about 1,000’ MSL in DSM to 5,500’ MSL in DEN, and then the peaks shoot up from there. But on the West side of the Front Range the ground levels off yet another thousand feet or two above DEN. And you can tell in an airplane flying at 37,000’ that the ground as you fly West is getting closer and closer. It’s odd. And it’s that elevation, and the changes in elevation going on throughout the region, that makes the rivers flow and do what they do.

I know I’m exposing the ineffectuality of our educational system--or my own dimness--as I look, gape-jawed, at what any kid is supposed to have grasped in the third grade. Still, the airplane gives you a perspective that is simply unavailable to someone on a ground, or even in a light plane flying 2,000’ above the terrain. One can see that a river--and not just the ones flowing in the high mountain plains, but down on the level, say, passing Omaha--is not just here and now, but a living thing which has left its mark on our planet over comparatively vast stretches of time. In the case of the Grand Canyon, it’s larger and more spectacular than what humans have wrought in their short tenure here (New York City in its entirety would fit in a side canyon invisible to the rest of its vastness); no vantage point on the ground would give you more than a small glimpse of the totality of the Grand Canyon, and it’s but one of a collection of similar features over a stretch of many miles.

But even around Omaha, the river has left a wide, meandering scar across the land, stretching in both directions as far as you can see and, of course, well beyond; and the pathway of its influence is many, many times wider than the river is presently. What may look recent in the river’s history--say, a one-time bend that is now filled with trees, or an exposed cliff where the land was eroded away--now has houses and roadways built on it and railroad tracks skirting its edges. And you realize that what appears very recent to the river is in fact probably much older than our presence here. This is the passage of time in scales beyond what our lives give us ready insight into. The pattern of farms and the square-mile grid which covers many whole states appear to have been lain upon the top. Indeed, that’s exactly what we’ve done. The larger features of the earth’s topography are clearly visible beneath our chicken scratching. Again, the view from an airplane six miles up makes all this apparent to one. It all gives you a sense of time and scale, and none of it would appear nearly this way from a canoe in the middle of the river (however cool that might be to see it).

No comments: